Rectangular Polar Parametric - Toomey

Copyright © 2011-2017 by Harold Toomey, WyzAnt Tutor 1

Harold’s Precalculus Rectangular – Polar – Parametric

“Cheat Sheet” 15 October 2017

Rectangular Polar Parametric

Point

𝑓(𝑥) = 𝑦 (𝑥, 𝑦) (𝑎, 𝑏)

•

(𝑟 , 𝜃) or 𝑟 ∠ 𝜃 Point (a,b) in Rectangular: 𝑥(𝑡) = 𝑎 𝑦(𝑡) = 𝑏 < 𝑎, 𝑏 >

𝑡 = 3𝑟𝑑 𝑣𝑎𝑟𝑖𝑎𝑏𝑙𝑒, 𝑢𝑠𝑢𝑎𝑙𝑙𝑦 𝑡𝑖𝑚𝑒,

with 1 degree of freedom (df)

Polar Rect.

𝑥 = 𝑟 cos 𝜃 𝑦 = 𝑟 𝑠𝑖𝑛 𝜃

𝑡𝑎𝑛 𝜃 =𝑦

𝑥

Rect. Polar

𝑟2 = 𝑥2 + 𝑦2

𝑟 = ± √𝑥2 + 𝑦2

𝜃 = 𝑡𝑎𝑛−1 (𝑦

𝑥)

Line

Slope-Intercept Form: 𝑦 = 𝑚𝑥 + 𝑏

Point-Slope Form:

𝑦 − 𝑦0 = 𝑚 (𝑥 − 𝑥0)

General Form: 𝐴𝑥 + 𝐵𝑦 + 𝐶 = 0

Calculus Form:

𝑓(𝑥) = 𝑓′(𝑎) 𝑥 + 𝑓(0)

< 𝑥, 𝑦 > = < 𝑥0, 𝑦0 > + 𝑡 < 𝑎, 𝑏 > < 𝑥, 𝑦 > = < 𝑥0 + 𝑎𝑡, 𝑦0 + 𝑏𝑡 >

where < 𝑎, 𝑏 > = < 𝑥2 − 𝑥1, 𝑦2 − 𝑦1 >

𝑥(𝑡) = 𝑥0 + 𝑡𝑎 𝑦(𝑡) = 𝑦0 + 𝑡𝑏

𝑚 =∆𝑦

∆𝑥=

𝑦2 − 𝑦1

𝑥2 − 𝑥1=

𝑏

𝑎

Plane 𝑛𝑥(𝑥 − 𝑥0)

+𝑛𝑦(𝑦 − 𝑦0)

+ 𝑛𝑧(𝑧 − 𝑧0) = 0

Vector Form: 𝒏 ⦁ (𝒓 − 𝒓0) = 0

𝒓 = 𝒓0 + 𝑠𝒗 + 𝑡𝒘

http://en.wikipedia.org/wiki/File:Polar_to_cartesian.svg

Rectangular Polar Parametric .


Conics

General Equation for All Conics:

𝐴𝑥2 + 𝐵𝑥𝑦 + 𝐶𝑦2 + 𝐷𝑥 + 𝐸𝑦 + 𝐹 = 0

where 𝐿𝑖𝑛𝑒: 𝐴 = 𝐵 = 𝐶 = 0 𝐶𝑖𝑟𝑐𝑙𝑒: 𝐴 = 𝐶 𝑎𝑛𝑑 𝐵 = 0 𝐸𝑙𝑙𝑖𝑝𝑠𝑒: 𝐴𝐶 > 0 𝑜𝑟 𝐵2 − 4𝐴𝐶 < 0 𝑃𝑎𝑟𝑎𝑏𝑜𝑙𝑎: 𝐴𝐶 = 0 or 𝐵2 − 4𝐴𝐶 = 0 𝐻𝑦𝑝𝑒𝑟𝑏𝑜𝑙𝑎: 𝐴𝐶 < 0 𝑜𝑟 𝐵2 − 4𝐴𝐶 > 0 Note: If 𝐴 + 𝐶 = 0, square hyperbola

Rotation: If B ≠ 0, then rotate coordinate system:

𝑐𝑜𝑡 2𝜃 =𝐴 − 𝐶

𝐵

𝑥 = 𝑥′ 𝑐𝑜𝑠 𝜃 − 𝑦′ 𝑠𝑖𝑛 𝜃 𝑦 = 𝑦′ 𝑐𝑜𝑠 𝜃 + 𝑥′ 𝑠𝑖𝑛 𝜃

New = (x’, y’), Old = (x, y)

rotates through angle 𝜃 from x-axis

General Equation for All Conics:

𝑟 =𝑝

1 − 𝑒 𝑐𝑜𝑠 𝜃

𝑤ℎ𝑒𝑟𝑒 𝑝 = { 𝑎 (1 − 𝑒2)

2𝑑 𝑎 (𝑒2 − 1)

𝑓𝑜𝑟 { 0 ≤ 𝑒 < 1

𝑒 = 1𝑒 > 1

p = semi-latus rectum

or the line segment running from the focus to the curve in a direction parallel to the

directrix

Eccentricity: 𝐶𝑖𝑟𝑐𝑙𝑒 𝑒 = 0𝐸𝑙𝑙𝑖𝑝𝑠𝑒 0 ≤ 𝑒 < 1𝑃𝑎𝑟𝑎𝑏𝑜𝑙𝑎 𝑒 = 1𝐻𝑦𝑝𝑒𝑟𝑏𝑜𝑙𝑎 𝑒 > 1

http://faculty.eicc.edu/bwood/ma155supplemental/supplemental31.htm



Circle

𝑥2 + 𝑦2 = 𝑟2 (𝑥 − ℎ)2 + (𝑦 − 𝑘)2 = 𝑟2

Center: (ℎ, 𝑘) Vertices: NA Focus: (ℎ, 𝑘)

(ℎ, 𝑘)

Centered at Origin: r = a (constant)

𝜃 = 𝜃 [0, 2𝜋] 𝑜𝑟 [0, 360°]

𝑥(𝑡) = 𝑟 𝑐𝑜𝑠(𝑡) + ℎ 𝑦(𝑡) = 𝑟 𝑠𝑖𝑛(𝑡) + 𝑘

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [0, 2𝜋)

(ℎ, 𝑘) = 𝑐𝑒𝑛𝑡𝑒𝑟 𝑜𝑓 𝑐𝑖𝑟𝑐𝑙𝑒



Ellipse

(𝑥 − ℎ)2

𝑎2+

(𝑦 − 𝑘)2

𝑏2= 1

Center: (ℎ, 𝑘)

Vertices: (ℎ ± 𝑎, 𝑘) and (ℎ, 𝑘 ± 𝑏) Foci: (ℎ ± 𝑐, 𝑘)

Focus length, c, from center:

𝑐 = √𝑎2 − 𝑏2

Ellipse:

𝑟 =𝑎 (1 − 𝑒2)

1 + 𝑒 𝑐𝑜𝑠 𝜃 𝑓𝑜𝑟 0 ≤ 𝑒 < 1

𝑤ℎ𝑒𝑟𝑒 𝑒 = 𝑐

𝑎=

√𝑎2 − 𝑏2

𝑎

relative to center (h,k)

Interesting Note: The sum of the distances from each focus

to a point on the curve is constant. |𝑑1 + 𝑑2| = 𝑘

𝑥(𝑡) = 𝑎 𝑐𝑜𝑠(𝑡) + ℎ 𝑦(𝑡) = 𝑏 𝑠𝑖𝑛(𝑡) + 𝑘

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [0, 2𝜋]

(ℎ, 𝑘) = 𝑐𝑒𝑛𝑡𝑒𝑟 𝑜𝑓 𝑒𝑙𝑙𝑖𝑝𝑠𝑒

Rotated Ellipse:

𝑥(𝑡) = 𝑎 𝑐𝑜𝑠 𝑡 𝑐𝑜𝑠 𝜃 − 𝑏 𝑠𝑖𝑛 𝑡 𝑠𝑖𝑛 𝜃 + ℎ 𝑦(𝑡) = 𝑎 𝑐𝑜𝑠 𝑡 𝑠𝑖𝑛 𝜃 + 𝑏 𝑠𝑖𝑛 𝑡 𝑐𝑜𝑠 𝜃 + 𝑘

𝜃 = the angle between the x-axis and the

major axis of the ellipse



Parabola

Vertical Axis of Symmetry: 𝑥2 = 4 𝑝𝑦

(𝑥 − ℎ)2 = 4𝑝(𝑦 − 𝑘) Vertex: (ℎ, 𝑘)

Focus: (ℎ, 𝑘 + 𝑝) Directrix: 𝑦 = 𝑘 − 𝑝

Horizontal Axis of Symmetry:

𝑦2 = 4 𝑝𝑥 (𝑦 − 𝑘)2 = 4𝑝(𝑥 − ℎ)

Vertex: (ℎ, 𝑘) Focus: (ℎ + 𝑝, 𝑘)

Directrix: 𝑥 = ℎ − 𝑝

Parabola:

𝑟 =2𝑑

1 + 𝑒 𝑐𝑜𝑠 𝜃 𝑓𝑜𝑟 𝑒 = 1

Trigonometric Form:

𝑦 = 𝑥2 𝑟 𝑠𝑖𝑛 𝜃 = 𝑟2 𝑐𝑜𝑠2 𝜃

𝑟 =𝑠𝑖𝑛 𝜃

𝑐𝑜𝑠2 𝜃= 𝑡𝑎𝑛 𝜃 𝑠𝑒𝑐 𝜃

Vertical Axis of Symmetry: 𝑥(𝑡) = 2𝑝𝑡 + ℎ

𝑦(𝑡) = 𝑝𝑡2 + 𝑘 (opens upwards) or 𝑦(𝑡) = −𝑝𝑡2 − 𝑘 (opens downwards)

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [−𝑐, 𝑐] (h, k) = vertex of parabola

Horizontal Axis of Symmetry: 𝑦(𝑡) = 2𝑝𝑡 + 𝑘

𝑥(𝑡) = 𝑝𝑡2 + ℎ (opens to the right) or 𝑥(𝑡) = −𝑝𝑡2 − ℎ (opens to the left)

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [−𝑐, 𝑐] (h, k) = vertex of parabola

Projectile Motion: 𝑥(𝑡) = 𝑥0 + 𝑣𝑥𝑡

𝑦(𝑡) = 𝑦0 + 𝑣𝑦𝑡 − 16𝑡2 feet

𝑦(𝑡) = 𝑦0 + 𝑣𝑦𝑡 − 4.9𝑡2 meters

𝑣𝑥 = 𝑣 𝑐𝑜𝑠 𝜃 𝑣𝑦 = 𝑣 𝑠𝑖𝑛 𝜃

General Form:

𝑥 = 𝐴𝑡2 + 𝐵𝑡 + 𝐶 𝑦 = 𝐷𝑡2 + 𝐸𝑡 + 𝐹

where A and D have the same sign



Hyperbola

(𝑥 − ℎ)2

𝑎2−

(𝑦 − 𝑘)2

𝑏2= 1

Center: (ℎ, 𝑘)

Vertices: (ℎ ± 𝑎, 𝑘) Foci: (ℎ ± 𝑐, 𝑘)

Focus length, c, from center:

𝑐 = √𝑎2 + 𝑏2

Hyperbola:

𝑟 =𝑎 (𝑒2 − 1)

1 + 𝑒 𝑐𝑜𝑠 𝜃 𝑓𝑜𝑟 𝑒 > 1

Eccentricity:

𝑤ℎ𝑒𝑟𝑒 𝑒 = 𝑐

𝑎=

√𝑎2 + 𝑏2

𝑎= sec 𝜃 > 1

relative to center (h,k)

p = semi-latus rectum or the line segment running from the focus

to the curve in the directions 𝜃 = ± 𝜋

2

Interesting Note:

The difference between the distances from each focus to a point on the curve is

constant. |𝑑1 − 𝑑2| = 𝑘

Left-Right Opening Hyperbola: 𝑥(𝑡) = 𝑎 𝑠𝑒𝑐( 𝑡) + ℎ 𝑦(𝑡) = 𝑏 𝑡𝑎𝑛( 𝑡) + 𝑘

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [−𝑐, 𝑐] (h, k) = vertex of hyperbola

Up-Down Opening Hyperbola: 𝑥(𝑡) = 𝑎 𝑡𝑎𝑛(𝑡) + ℎ 𝑦(𝑡) = 𝑏 𝑠𝑒𝑐(𝑡) + 𝑘

[𝑡𝑚𝑖𝑛, 𝑡𝑚𝑎𝑥] = [−𝑐, 𝑐] (h, k) = vertex of hyperbola

General Form: 𝑥(𝑡) = 𝐴𝑡2 + 𝐵𝑡 + 𝐶 𝑦(𝑡) = 𝐷𝑡2 + 𝐸𝑡 + 𝐹

where A and D have different signs

Inverse Functions

𝑓(𝑓−1 (𝑥)) = 𝑓−1 (𝑓(𝑥)) = 𝑥

Inverse Function Theorem:

𝑓−1(𝑏) = 1

𝑓′(𝑎)

where 𝑏 = 𝑓′(𝑎)

if 𝑦 = 𝑠𝑖𝑛 𝜃 𝑖𝑓 𝑦 = 𝑐𝑜𝑠 𝜃 𝑖𝑓 𝑦 = 𝑡𝑎𝑛 𝜃

if 𝑦 = 𝑐𝑠𝑐 𝜃 if 𝑦 = 𝑠𝑒𝑐 𝜃 𝑖𝑓 𝑦 = 𝑐𝑜𝑡 𝜃

𝑡ℎ𝑒𝑛 𝜃 = 𝑠𝑖𝑛−1 𝑦 𝑡ℎ𝑒𝑛 𝜃 = 𝑐𝑜𝑠−1 𝑦 𝑡ℎ𝑒𝑛 𝜃 = 𝑡𝑎𝑛−1 𝑦

𝑡ℎ𝑒𝑛 𝜃 = 𝑐𝑠𝑐−1 𝑦 𝑡ℎ𝑒𝑛 𝜃 = 𝑠𝑒𝑐−1 𝑦 𝑡ℎ𝑒𝑛 𝜃 = 𝑐𝑜𝑡−1 𝑦

𝜃 = arcsin 𝑦 𝜃 = arccos 𝑦 𝜃 = 𝑎𝑟𝑐𝑡𝑎𝑛 𝑦 𝜃 = 𝑎𝑟𝑐𝑐𝑠𝑐 𝑦 𝜃 = 𝑎𝑟𝑐𝑠𝑒𝑐 𝑦 𝜃 = 𝑎𝑟𝑐𝑐𝑜𝑡 𝑦



Arc Length

Circle: 𝐿 = 𝑠 = 𝑟𝜃

Proof:

𝐿 = (𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝑐𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒) ∙ 𝜋 ∙ (𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟)

𝐿 = (𝜃

2𝜋) 𝜋 (2𝑟) = 𝑟𝜃

Perimeter Square: P = 4s

Rectangle: P = 2l + 2w Triangle: P = a + b + c

Circle: C = πd = 2πr Ellipse: 𝐶 ≈ 𝜋(𝑎 + 𝑏)

Area

Square: A = s² Rectangle: A = lw

Rhombus: A = ½ ab Parallelogram: A = bh

Trapezoid: 𝐴 =(𝑏1+𝑏2)

2 ℎ

Kite: 𝐴 = 𝑑1 𝑑2

2

Triangle: A = ½ bh Triangle: A = ½ ab sin(C)

Triangle: 𝐴 = √𝑠(𝑠 − 𝑎)(𝑠 − 𝑏)(𝑠 − 𝑐),

𝑤ℎ𝑒𝑟𝑒 𝑠 =𝑎+𝑏+𝑐

2

Equilateral Triangle: 𝐴 = ¼√3𝑠2

Frustum: 𝐴 =1

3(

𝑏1+𝑏2

2) ℎ

Circle: A = πr²

Circular Sector: A = ½ r²𝜃 Ellipse: A = πab

Lateral Surface

Area

Cylinder: S = 2πrh Cone: S = πrl

Total Surface

Area

Cube: S = 6s² Rectangular Box: S = 2lw + 2wh + 2hl

Regular Tetrahedron: S = 2bh Cylinder: S = 2πr (r + h)

Cone: S = πr² + πrl = πr (r + l)

Sphere: S = 4πr² Ellipsoid: S = (too complex)

Volume

Cube: V = s³ Rectangular Prism: V = lwh

Cylinder: V = πr²h Triangular Prism: V= Bh

Tetrahedron: V= ⅓ bh Pyramid: V = ⅓ Bh

Cone: V = ⅓ bh = ⅓ πr²h

Sphere: 𝑉 =4

3𝜋𝑟3

Ellipsoid: V = 4

3 πabc

Rectangular Polar Parametric - Toomey

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